xref: /openbmc/linux/drivers/input/serio/libps2.c (revision 5d331b7f) 
1 /*
2  * PS/2 driver library
3  *
4  * Copyright (c) 1999-2002 Vojtech Pavlik
5  * Copyright (c) 2004 Dmitry Torokhov
6  */
7 
8 /*
9  * This program is free software; you can redistribute it and/or modify it
10  * under the terms of the GNU General Public License version 2 as published by
11  * the Free Software Foundation.
12  */
13 
14 #include <linux/delay.h>
15 #include <linux/module.h>
16 #include <linux/sched.h>
17 #include <linux/interrupt.h>
18 #include <linux/input.h>
19 #include <linux/serio.h>
20 #include <linux/i8042.h>
21 #include <linux/libps2.h>
22 
23 #define DRIVER_DESC	"PS/2 driver library"
24 
25 MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
26 MODULE_DESCRIPTION("PS/2 driver library");
27 MODULE_LICENSE("GPL");
28 
29 static int ps2_do_sendbyte(struct ps2dev *ps2dev, u8 byte,
30 			   unsigned int timeout, unsigned int max_attempts)
31 	__releases(&ps2dev->serio->lock) __acquires(&ps2dev->serio->lock)
32 {
33 	int attempt = 0;
34 	int error;
35 
36 	lockdep_assert_held(&ps2dev->serio->lock);
37 
38 	do {
39 		ps2dev->nak = 1;
40 		ps2dev->flags |= PS2_FLAG_ACK;
41 
42 		serio_continue_rx(ps2dev->serio);
43 
44 		error = serio_write(ps2dev->serio, byte);
45 		if (error)
46 			dev_dbg(&ps2dev->serio->dev,
47 				"failed to write %#02x: %d\n", byte, error);
48 		else
49 			wait_event_timeout(ps2dev->wait,
50 					   !(ps2dev->flags & PS2_FLAG_ACK),
51 					   msecs_to_jiffies(timeout));
52 
53 		serio_pause_rx(ps2dev->serio);
54 	} while (ps2dev->nak == PS2_RET_NAK && ++attempt < max_attempts);
55 
56 	ps2dev->flags &= ~PS2_FLAG_ACK;
57 
58 	if (!error) {
59 		switch (ps2dev->nak) {
60 		case 0:
61 			break;
62 		case PS2_RET_NAK:
63 			error = -EAGAIN;
64 			break;
65 		case PS2_RET_ERR:
66 			error = -EPROTO;
67 			break;
68 		default:
69 			error = -EIO;
70 			break;
71 		}
72 	}
73 
74 	if (error || attempt > 1)
75 		dev_dbg(&ps2dev->serio->dev,
76 			"%02x - %d (%x), attempt %d\n",
77 			byte, error, ps2dev->nak, attempt);
78 
79 	return error;
80 }
81 
82 /*
83  * ps2_sendbyte() sends a byte to the device and waits for acknowledge.
84  * It doesn't handle retransmission, the caller is expected to handle
85  * it when needed.
86  *
87  * ps2_sendbyte() can only be called from a process context.
88  */
89 
90 int ps2_sendbyte(struct ps2dev *ps2dev, u8 byte, unsigned int timeout)
91 {
92 	int retval;
93 
94 	serio_pause_rx(ps2dev->serio);
95 
96 	retval = ps2_do_sendbyte(ps2dev, byte, timeout, 1);
97 	dev_dbg(&ps2dev->serio->dev, "%02x - %x\n", byte, ps2dev->nak);
98 
99 	serio_continue_rx(ps2dev->serio);
100 
101 	return retval;
102 }
103 EXPORT_SYMBOL(ps2_sendbyte);
104 
105 void ps2_begin_command(struct ps2dev *ps2dev)
106 {
107 	struct mutex *m = ps2dev->serio->ps2_cmd_mutex ?: &ps2dev->cmd_mutex;
108 
109 	mutex_lock(m);
110 }
111 EXPORT_SYMBOL(ps2_begin_command);
112 
113 void ps2_end_command(struct ps2dev *ps2dev)
114 {
115 	struct mutex *m = ps2dev->serio->ps2_cmd_mutex ?: &ps2dev->cmd_mutex;
116 
117 	mutex_unlock(m);
118 }
119 EXPORT_SYMBOL(ps2_end_command);
120 
121 /*
122  * ps2_drain() waits for device to transmit requested number of bytes
123  * and discards them.
124  */
125 
126 void ps2_drain(struct ps2dev *ps2dev, size_t maxbytes, unsigned int timeout)
127 {
128 	if (maxbytes > sizeof(ps2dev->cmdbuf)) {
129 		WARN_ON(1);
130 		maxbytes = sizeof(ps2dev->cmdbuf);
131 	}
132 
133 	ps2_begin_command(ps2dev);
134 
135 	serio_pause_rx(ps2dev->serio);
136 	ps2dev->flags = PS2_FLAG_CMD;
137 	ps2dev->cmdcnt = maxbytes;
138 	serio_continue_rx(ps2dev->serio);
139 
140 	wait_event_timeout(ps2dev->wait,
141 			   !(ps2dev->flags & PS2_FLAG_CMD),
142 			   msecs_to_jiffies(timeout));
143 
144 	ps2_end_command(ps2dev);
145 }
146 EXPORT_SYMBOL(ps2_drain);
147 
148 /*
149  * ps2_is_keyboard_id() checks received ID byte against the list of
150  * known keyboard IDs.
151  */
152 
153 bool ps2_is_keyboard_id(u8 id_byte)
154 {
155 	static const u8 keyboard_ids[] = {
156 		0xab,	/* Regular keyboards		*/
157 		0xac,	/* NCD Sun keyboard		*/
158 		0x2b,	/* Trust keyboard, translated	*/
159 		0x5d,	/* Trust keyboard		*/
160 		0x60,	/* NMB SGI keyboard, translated */
161 		0x47,	/* NMB SGI keyboard		*/
162 	};
163 
164 	return memchr(keyboard_ids, id_byte, sizeof(keyboard_ids)) != NULL;
165 }
166 EXPORT_SYMBOL(ps2_is_keyboard_id);
167 
168 /*
169  * ps2_adjust_timeout() is called after receiving 1st byte of command
170  * response and tries to reduce remaining timeout to speed up command
171  * completion.
172  */
173 
174 static int ps2_adjust_timeout(struct ps2dev *ps2dev,
175 			      unsigned int command, unsigned int timeout)
176 {
177 	switch (command) {
178 	case PS2_CMD_RESET_BAT:
179 		/*
180 		 * Device has sent the first response byte after
181 		 * reset command, reset is thus done, so we can
182 		 * shorten the timeout.
183 		 * The next byte will come soon (keyboard) or not
184 		 * at all (mouse).
185 		 */
186 		if (timeout > msecs_to_jiffies(100))
187 			timeout = msecs_to_jiffies(100);
188 		break;
189 
190 	case PS2_CMD_GETID:
191 		/*
192 		 * Microsoft Natural Elite keyboard responds to
193 		 * the GET ID command as it were a mouse, with
194 		 * a single byte. Fail the command so atkbd will
195 		 * use alternative probe to detect it.
196 		 */
197 		if (ps2dev->cmdbuf[1] == 0xaa) {
198 			serio_pause_rx(ps2dev->serio);
199 			ps2dev->flags = 0;
200 			serio_continue_rx(ps2dev->serio);
201 			timeout = 0;
202 		}
203 
204 		/*
205 		 * If device behind the port is not a keyboard there
206 		 * won't be 2nd byte of ID response.
207 		 */
208 		if (!ps2_is_keyboard_id(ps2dev->cmdbuf[1])) {
209 			serio_pause_rx(ps2dev->serio);
210 			ps2dev->flags = ps2dev->cmdcnt = 0;
211 			serio_continue_rx(ps2dev->serio);
212 			timeout = 0;
213 		}
214 		break;
215 
216 	default:
217 		break;
218 	}
219 
220 	return timeout;
221 }
222 
223 /*
224  * ps2_command() sends a command and its parameters to the mouse,
225  * then waits for the response and puts it in the param array.
226  *
227  * ps2_command() can only be called from a process context
228  */
229 
230 int __ps2_command(struct ps2dev *ps2dev, u8 *param, unsigned int command)
231 {
232 	unsigned int timeout;
233 	unsigned int send = (command >> 12) & 0xf;
234 	unsigned int receive = (command >> 8) & 0xf;
235 	int rc;
236 	int i;
237 	u8 send_param[16];
238 
239 	if (receive > sizeof(ps2dev->cmdbuf)) {
240 		WARN_ON(1);
241 		return -EINVAL;
242 	}
243 
244 	if (send && !param) {
245 		WARN_ON(1);
246 		return -EINVAL;
247 	}
248 
249 	memcpy(send_param, param, send);
250 
251 	serio_pause_rx(ps2dev->serio);
252 
253 	ps2dev->flags = command == PS2_CMD_GETID ? PS2_FLAG_WAITID : 0;
254 	ps2dev->cmdcnt = receive;
255 	if (receive && param)
256 		for (i = 0; i < receive; i++)
257 			ps2dev->cmdbuf[(receive - 1) - i] = param[i];
258 
259 	/* Signal that we are sending the command byte */
260 	ps2dev->flags |= PS2_FLAG_ACK_CMD;
261 
262 	/*
263 	 * Some devices (Synaptics) peform the reset before
264 	 * ACKing the reset command, and so it can take a long
265 	 * time before the ACK arrives.
266 	 */
267 	timeout = command == PS2_CMD_RESET_BAT ? 1000 : 200;
268 
269 	rc = ps2_do_sendbyte(ps2dev, command & 0xff, timeout, 2);
270 	if (rc)
271 		goto out_reset_flags;
272 
273 	/* Now we are sending command parameters, if any */
274 	ps2dev->flags &= ~PS2_FLAG_ACK_CMD;
275 
276 	for (i = 0; i < send; i++) {
277 		rc = ps2_do_sendbyte(ps2dev, param[i], 200, 2);
278 		if (rc)
279 			goto out_reset_flags;
280 	}
281 
282 	serio_continue_rx(ps2dev->serio);
283 
284 	/*
285 	 * The reset command takes a long time to execute.
286 	 */
287 	timeout = msecs_to_jiffies(command == PS2_CMD_RESET_BAT ? 4000 : 500);
288 
289 	timeout = wait_event_timeout(ps2dev->wait,
290 				     !(ps2dev->flags & PS2_FLAG_CMD1), timeout);
291 
292 	if (ps2dev->cmdcnt && !(ps2dev->flags & PS2_FLAG_CMD1)) {
293 
294 		timeout = ps2_adjust_timeout(ps2dev, command, timeout);
295 		wait_event_timeout(ps2dev->wait,
296 				   !(ps2dev->flags & PS2_FLAG_CMD), timeout);
297 	}
298 
299 	serio_pause_rx(ps2dev->serio);
300 
301 	if (param)
302 		for (i = 0; i < receive; i++)
303 			param[i] = ps2dev->cmdbuf[(receive - 1) - i];
304 
305 	if (ps2dev->cmdcnt &&
306 	    (command != PS2_CMD_RESET_BAT || ps2dev->cmdcnt != 1)) {
307 		rc = -EPROTO;
308 		goto out_reset_flags;
309 	}
310 
311 	rc = 0;
312 
313  out_reset_flags:
314 	ps2dev->flags = 0;
315 	serio_continue_rx(ps2dev->serio);
316 
317 	dev_dbg(&ps2dev->serio->dev,
318 		"%02x [%*ph] - %x/%08lx [%*ph]\n",
319 		command & 0xff, send, send_param,
320 		ps2dev->nak, ps2dev->flags,
321 		receive, param ?: send_param);
322 
323 	/*
324 	 * ps_command() handles resends itself, so do not leak -EAGAIN
325 	 * to the callers.
326 	 */
327 	return rc != -EAGAIN ? rc : -EPROTO;
328 }
329 EXPORT_SYMBOL(__ps2_command);
330 
331 int ps2_command(struct ps2dev *ps2dev, u8 *param, unsigned int command)
332 {
333 	int rc;
334 
335 	ps2_begin_command(ps2dev);
336 	rc = __ps2_command(ps2dev, param, command);
337 	ps2_end_command(ps2dev);
338 
339 	return rc;
340 }
341 EXPORT_SYMBOL(ps2_command);
342 
343 /*
344  * ps2_sliced_command() sends an extended PS/2 command to the mouse
345  * using sliced syntax, understood by advanced devices, such as Logitech
346  * or Synaptics touchpads. The command is encoded as:
347  * 0xE6 0xE8 rr 0xE8 ss 0xE8 tt 0xE8 uu where (rr*64)+(ss*16)+(tt*4)+uu
348  * is the command.
349  */
350 
351 int ps2_sliced_command(struct ps2dev *ps2dev, u8 command)
352 {
353 	int i;
354 	int retval;
355 
356 	ps2_begin_command(ps2dev);
357 
358 	retval = __ps2_command(ps2dev, NULL, PS2_CMD_SETSCALE11);
359 	if (retval)
360 		goto out;
361 
362 	for (i = 6; i >= 0; i -= 2) {
363 		u8 d = (command >> i) & 3;
364 		retval = __ps2_command(ps2dev, &d, PS2_CMD_SETRES);
365 		if (retval)
366 			break;
367 	}
368 
369 out:
370 	dev_dbg(&ps2dev->serio->dev, "%02x - %d\n", command, retval);
371 	ps2_end_command(ps2dev);
372 	return retval;
373 }
374 EXPORT_SYMBOL(ps2_sliced_command);
375 
376 /*
377  * ps2_init() initializes ps2dev structure
378  */
379 
380 void ps2_init(struct ps2dev *ps2dev, struct serio *serio)
381 {
382 	mutex_init(&ps2dev->cmd_mutex);
383 	lockdep_set_subclass(&ps2dev->cmd_mutex, serio->depth);
384 	init_waitqueue_head(&ps2dev->wait);
385 	ps2dev->serio = serio;
386 }
387 EXPORT_SYMBOL(ps2_init);
388 
389 /*
390  * ps2_handle_ack() is supposed to be used in interrupt handler
391  * to properly process ACK/NAK of a command from a PS/2 device.
392  */
393 
394 bool ps2_handle_ack(struct ps2dev *ps2dev, u8 data)
395 {
396 	switch (data) {
397 	case PS2_RET_ACK:
398 		ps2dev->nak = 0;
399 		break;
400 
401 	case PS2_RET_NAK:
402 		ps2dev->flags |= PS2_FLAG_NAK;
403 		ps2dev->nak = PS2_RET_NAK;
404 		break;
405 
406 	case PS2_RET_ERR:
407 		if (ps2dev->flags & PS2_FLAG_NAK) {
408 			ps2dev->flags &= ~PS2_FLAG_NAK;
409 			ps2dev->nak = PS2_RET_ERR;
410 			break;
411 		}
412 
413 	/*
414 	 * Workaround for mice which don't ACK the Get ID command.
415 	 * These are valid mouse IDs that we recognize.
416 	 */
417 	case 0x00:
418 	case 0x03:
419 	case 0x04:
420 		if (ps2dev->flags & PS2_FLAG_WAITID) {
421 			ps2dev->nak = 0;
422 			break;
423 		}
424 		/* Fall through */
425 	default:
426 		/*
427 		 * Do not signal errors if we get unexpected reply while
428 		 * waiting for an ACK to the initial (first) command byte:
429 		 * the device might not be quiesced yet and continue
430 		 * delivering data.
431 		 * Note that we reset PS2_FLAG_WAITID flag, so the workaround
432 		 * for mice not acknowledging the Get ID command only triggers
433 		 * on the 1st byte; if device spews data we really want to see
434 		 * a real ACK from it.
435 		 */
436 		dev_dbg(&ps2dev->serio->dev, "unexpected %#02x\n", data);
437 		ps2dev->flags &= ~PS2_FLAG_WAITID;
438 		return ps2dev->flags & PS2_FLAG_ACK_CMD;
439 	}
440 
441 	if (!ps2dev->nak) {
442 		ps2dev->flags &= ~PS2_FLAG_NAK;
443 		if (ps2dev->cmdcnt)
444 			ps2dev->flags |= PS2_FLAG_CMD | PS2_FLAG_CMD1;
445 	}
446 
447 	ps2dev->flags &= ~PS2_FLAG_ACK;
448 	wake_up(&ps2dev->wait);
449 
450 	if (data != PS2_RET_ACK)
451 		ps2_handle_response(ps2dev, data);
452 
453 	return true;
454 }
455 EXPORT_SYMBOL(ps2_handle_ack);
456 
457 /*
458  * ps2_handle_response() is supposed to be used in interrupt handler
459  * to properly store device's response to a command and notify process
460  * waiting for completion of the command.
461  */
462 
463 bool ps2_handle_response(struct ps2dev *ps2dev, u8 data)
464 {
465 	if (ps2dev->cmdcnt)
466 		ps2dev->cmdbuf[--ps2dev->cmdcnt] = data;
467 
468 	if (ps2dev->flags & PS2_FLAG_CMD1) {
469 		ps2dev->flags &= ~PS2_FLAG_CMD1;
470 		if (ps2dev->cmdcnt)
471 			wake_up(&ps2dev->wait);
472 	}
473 
474 	if (!ps2dev->cmdcnt) {
475 		ps2dev->flags &= ~PS2_FLAG_CMD;
476 		wake_up(&ps2dev->wait);
477 	}
478 
479 	return true;
480 }
481 EXPORT_SYMBOL(ps2_handle_response);
482 
483 void ps2_cmd_aborted(struct ps2dev *ps2dev)
484 {
485 	if (ps2dev->flags & PS2_FLAG_ACK)
486 		ps2dev->nak = 1;
487 
488 	if (ps2dev->flags & (PS2_FLAG_ACK | PS2_FLAG_CMD))
489 		wake_up(&ps2dev->wait);
490 
491 	/* reset all flags except last nack */
492 	ps2dev->flags &= PS2_FLAG_NAK;
493 }
494 EXPORT_SYMBOL(ps2_cmd_aborted);
495